Most, if not all of the difference in lung cancer mortality between US blacks and whites can be explained by differences in socioeconomic status (SES). Harlem has the highest death rate from lung cancer in New York City and has the highest proportion of families below the poverty line of all the communities in this City. Early age at presentation and rapid demise following diagnosis are prominent features of lung cancer as seen at Harlem Hospital. The activation of cellular oncogenes and growth factors, including ras, myc and TGF-beta, appears to play a critical role in the carcinogenic process. These activated genes exert their effect through their protein products which are often measurable in serum and can therefore serve as surrogates for oncogene activation. There has not been a study comparing oncogene activation and expression of growth factors in blacks and whites. Over a 5-year period, the proposed case-comparison study will recruit 70 African-American patients with lung cancer stages I through IIIa from Harlem and Presbyterian Hospital. They will be compared to an equal number of white patients individually matched for age group, smoking and stage at diagnosis. They will be administered a questionnaire relating to exposure to carcinogens, diet, and socio-economic factors. Serum will be analyzed for the protein products of ras and myc, and TGF-beta. We will test the hypotheses that, after controlling for cigarette smoking, stage at presentation and age group, there will be significant differences in the frequency of detection of these oncoproteins in the serum of whites and blacks; that the frequency of oncoprotein detection will increase with more advanced stage and that it will correlate with survival in both groups, as well as with socioeconomic indices and possibly diet and exposure to carcinogens.